Bio 180 Ch 1

Front 1

Matter -

Back 1

Takes up space and has mass

Front 2

Element -

Back 2

Cannot be broken down to other substances by chemical reactions

Front 3

Compound -

Back 3

Substance containing two or more elements

Front 4

Essential elements -

Back 4

A chemical element required for an organism to survive, grow, and reproduce.

Front 5

Trace elements -

Back 5

An element indispensable for life but required in extremely minute amounts.

Front 6

Atom -

Back 6

The smallest unit of matter that retains the properties of an element.

Front 7

Proton -

Back 7

A subatomic particle with a single positive electrical charge, with a mass of about 1.7x10^-24 g, found in the nucleus of an atom.

Front 8

Neutron -

Back 8

A subatomic particle having no electrical charge, with a mass of about 1.7x10^-24 g, found in the nucleus of an atom.

Front 9

Electron -

Back 9

A subatomic particle with a single negative electrical charge and a mass of about 1/2000 that of a neutron or proton. One or more electrons move around the nucleus of an atom.

Front 10

Atomic nucleus -

Back 10

An atom's dense, central core, containing protons and neutrons.

Front 11

Dalton -

Back 11

A measure of mass for atoms and subatomic particles; the same as one atomic mass unit (amu).

Front 12

Atomic number -

Back 12

The number of protons in the nucleus, unique for each element and designated by a subscript to the left of the elemental symbol.

Front 13

Mass number -

Back 13

The sum of the number of protons and neutrons in an atom's nucleus.

Front 14

Atomic mass -

Back 14

The total mass of an atom, which is the mass in grams of 1 mole of the atom.

Front 15

Mole -

Back 15

The number of grams of a substance that equals its molecular weight in daltons and contains Avogadro's number of molecules.

Front 16

Isotopes -

Back 16

One of several atomic forms of an element, each with the same number of protons but with a different number of neutrons; thus differing in atomic mass.

Front 17

Radioactive isotope -

Back 17

An isotope that is unstable; the nucleus decays spontaneously, giving off detectable particles and energy.

Front 18

Half-life

Back 18

The amount of time it takes for 50% of a sample of a radioactive isotope to decay.

Front 19

Radioactive dating -

Back 19

A method for determining the absolute age of rocks and fossils, based on the half-life of radioactive isotopes.

Front 20

Exponential decay formula

Back 20

N=Noe^-0.693t/T1/2

Front 21

Energy -

Back 21

The capacity to cause change, i.e. to do work.

Front 22

Potential energy -

Back 22

Energy that matter possesses because of its location or structure.

Front 23

Electron shells -

Back 23

An energy level of electrons at a characteristic average distance from the nucleus of an atom.

Front 24

Valence electrons -

Back 24

An electron in the outermost electron shell.

Front 25

Valence shell -

Back 25

The outermost energy shell of an atom, containing the valence electrons involved in the chemical reactions of that atom.

Front 26

Orbital -

Back 26

The 3D space where an electron is found 90% of the time.

Front 27

S orbital -

Back 27

The first and second electron shells that are shaped spherically that can hold 2 electrons each.

Front 28

P orbital -

Back 28

The second and higher electron shells that are dumbbell shaped that can hold no more than 2 electrons in each orbital.

Front 29

How many elements are naturally occurring in nature?

Back 29

92

Front 30

What are the four elements that make up 96% of living matter?

Back 30

Carbon, hydrogen, oxygen, and nitrogen.

Front 31

The properties of protons:

Back 31

1. It contributes mass of the nucleus of an atom
2. It contains a positive electrical charge
3. Weighs approx. 1.66x10^-24 g (~1 dalton)

Front 32

The properties of neutrons:

Back 32

1. It contributes mass of the nucleus of an atom
2. It has no electrical charge
3. Weighs approx. 1.66x10^-24 g (~1 dalton)

Front 33

The properties of electrons:

Back 33

1. Determines the charge and bonding properties of an atom
2. It contains a negative electrical charge
3. Weighs approx. 1/2000 the mass of a proton or neutron
4. Found in electron clouds of the atom

Front 34

What is different about the atomic number of an atom?

Back 34

The atomic number is unique for each element based on the number of protons in the nucleus

Front 35

How do you calculate how many neutrons are in the nucleus of an atom?

Back 35

Mass # - atomic # = neutrons of the atom

Front 36

What can be said about isotopes?

Back 36

1. Isotopes vary in the number of neutrons an element contains in its nucleus
2. Isotopes behave exactly like each of its other isotopes.

Front 37

What is true about radioactive isotopes?

Back 37

These are unstable isotopes that emit particles as radioactivity to lower its energy to a more stable energy state.

Front 38

What is an alpha particle?

Back 38

alpha - Contains 2 protons and 2 neutrons, essentially making it a Helium atom

Front 39

What is a beta particle?

Back 39

beta - Contains 1 proton and no neutrons, with a mass number of 0 and an atomic number of 1.

Front 40

What is a gamma particle?

Back 40

gamma - Contains 1 neutron and no proton, making the mass number 1 and atomic number 0.
Gamma particles do not change the nucleus of an atom.

Front 41

What happens to the electrons in an atom when it absorbs energy?

Back 41

The electron moves to a higher energy state by absorption excitation.

Front 42

What happens to the electrons in an atom when it emits energy?

Back 42

The electron moves to a lower energy state by fluorescence emission.

Front 43

What is the difference between electron (energy) shells and electron orbitals?

Back 43

Shell - the energy level of the atom;
Orbital - the 3D space in the atom where the electron can be found.

Front 44

What are valence shells and valence electrons?

Back 44

Shell - The outermost energy shell of an atom;
Electron - The electron in the outermost shell of an atom.

Front 45

What is the significance of the electron configuration in an atom?

Back 45

If an atom holds 8 electrons in its valence shell it is unreactive; if there are 7 or less electrons in the shell that atom is said to be chemically active.
Atoms with the same number of electrons in their valence shells have similar chemical properties.

Front 46

How does potential energy of an atom change with increasing electron shells?

Back 46

The potential energy of an electron increases with the increasing number of electron shells in an atom due to the requirement to move electrons away from the nucleus.

Front 47

What level of energy does the first shell of an atom contain; highest or lowest?

Back 47

Lowest due to the smallest volume of that shell.

Front 48

How are electrons excited?

Back 48

An input of energy can boost electrons to a higher energy shell by absorption of that energy.

Front 49

How is energy of an electron emitted?

Back 49

The electron releases energy by way of fluorescent light and moves to a lower energy state.

Front 50

How many electrons does the first shell of an atom hold?

Back 50

2

Front 51

How many electrons does the second and higher shells of an atom hold?

Back 51

8

Front 52

What are the chemical characteristics of an element based on?

Back 52

How many valence electrons are in the valence shell.
Elements with the same number of valence electrons have similar chemical properties.

Front 53

How many orbitals does the first shell of an atom have?

Back 53

2: 1s

Front 54

How many orbitals does the second shell of an atom have?

Back 54

4: 2s, 2px, 2py, 2pz

Front 55

How does an unpaired electron affect an atom?

Back 55

An unpaired electron in one or more orbitals is responsible for the reactivity of an atom.

Front 56

chemical bond -

Back 56

An attraction between two atoms, resulting from a sharing outer-shell electrons or the presence of opposite charges on the atom. The bonded atoms gain complete outer electron shells.

Front 57

Covalent bond -

Back 57

A type of strong chemical bond in which atoms share one or more pairs of valence electrons.

Front 58

Molecule -

Back 58

Two or more atoms held together by covalent bonds.

Front 59

Compound -

Back 59

A substance consisting of two or more different elements combined in a fixed ratio.

Front 60

Molecular formula -

Back 60

A formula for a compound that indicates how many of each atom are present in the compound.

Front 61

Lewis Dot Structure -

Back 61

Electron sharing can be depicted by an electron distribution diagram in which element symbols are surrounded by dots that represent the valence electrons (i.e. H:H for H2)

Front 62

Structural formula -

Back 62

Electron sharing can be depicted in which element symbols are connected by a dash in between them to represent a bond (H-H for H2)

Front 63

Space-filling model -

Back 63

This model comes closest to representing the actual shape of the molecule.

Front 64

Single bond -

Back 64

A pair of shared electrons (valence) by two atoms by one covalent bond (sigma bond).

Front 65

Double bond -

Back 65

A double covalent bond; the sharing of two pairs of valence electrons by two atoms by one sigma bond and one pi bond.

Front 66

Valence -

Back 66

The bonding capacity of a given atom; usually equals the number of unpaired electrons required to complete the atom's outermost (valence) shell.

Front 67

Electronegativity -

Back 67

The attraction of a given atom for the electrons of a covalent bond.

Front 68

Nonpolar covalent bond -

Back 68

A type of covalent bond in which electrons are shared equally between two atoms of similar electronegativities.

Front 69

Polar covalent bond -

Back 69

A covalent bond between atoms that differ in electronegativity. The shared electrons are pulled closer to the more electronegative atom, making it slightly negative and the other atom slightly positive.

Front 70

Ionic bond -

Back 70

A chemical bond resulting from the attraction between two oppositely charged ions.

Front 71

Ion -

Back 71

An atom or group of atoms that has gained or lost one or more electrons, thus acquiring a charge.

Front 72

Anion -

Back 72

A negatively charged ion.

Front 73

Cation -

Back 73

A positively charged ion.

Front 74

Dipole -

Back 74

The separation of positive and negative charges by some space.

Front 75

Salt -

Back 75

A compound formed by an ionic bond; also called an ionic compound.

Front 76

Hydrogen bond -

Back 76

A type of weak chemical bond formed when the slightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond in another molecule or in another region of the same molecule.

Front 77

Van der Waals interactions -

Back 77

Weak interactions between molecules or parts of molecules that result from the transient local partial charges.

Front 78

Tetrahedron -

Back 78

A central atom is located at the center with four substituents that are located at the corners of a tetrahedron.

Front 79

How are ionic and hydrogen bonds similar? How do they differ?

Back 79

They both have positive and negative attractions but hydrogen bonding deals with how hydrogen is attracted to other negatively charged atoms.

Front 80

Why are weak bonds so important in biology and how does its shape influence the biological activity of a molecule?

Back 80

They help to determine the shape and stability of biological molecules.
In protein, the secondary structures of alpha helixes and beta pleated sheets. Also in DNA

Front 81

Group the following types into strong or weak categories. Why do the atoms stay together in the bond and give an example.
Hydrogen bonds

Ionic bonds

Nonpolar covalent bonds

Polar covalent bonds

Van der Waals interactions

Back 81

Hydrogen bonds - WEAK - Atoms stay together by electrostatic attraction between a polar hydrogen and another polar electronegative atom. More polar atoms form stronger hydrogen bonds. (N-H, O-H, or F-H)
Ioninc bonds - Strength depends on ionic charges - Electrostatic attractions between oppositely charged ions (NaCl, MgCl2)

Nonpolar covalent bonds - STRONG - equal electronegativity on bonded atoms

Polar covalent bonds - STRONG - Unequal electronegativity on bonded atoms, creates dipole
van der Waals interactions - WEAK - Dipole-dipole interactions (ever-changing region of positive and negative charges). Individually weak but collectively strong.

Front 82

In the term trace element, the adjective trace means that:

a. The element is required in small amounts;

b. The element can be used as a label to trace atoms through an organism's metabolism;

c. The element is very rare on Earth;

d. The element enhances health but is not essential for the organism's long-term survival;

e. The element passes rapidly through the organism.

Back 82

a. The element is required in small amounts.

Front 83

Compared with 31P, the radioactive isotope 32P has:

a. A different atomic number;

b. A different charge;

c. One more proton;

d. One more electron;

e. One more neutron.

Back 83

e. One more neutron.

Front 84

The reactivity of an atom arises from:

a. The average distance of the outermost electron shell from the nucleus;

b. The existence of unpaired electrons in the valence shell;

c. The sum of the potential energies of all the electron shells;

d. The potential energy of the valence shell;

e. The energy differences between the s and p orbitals.

Back 84

b. The existence of unpaired electrons in the valence shell.

Front 85

Which statement is true of all atoms that are anions?

a. The atom has more electrons than protons;

b. The atom has more protons than electrons;

c. The atom has fewer protons than does a neutral atom of the same element;

d. The atom has more neutrons than protons;

e. The net charge is 1-.

Back 85

a. The atom has more electrons than protons.

Front 86

Which of the following statements correctly describes any chemical reaction that has reached equilibrium?

a. The concentrations of products and reactants are equal;

b. The reaction is now irreversible;

c. Both forward and reverse reactions have halted;

d. The rates of the forward and reverse reactions are equal;

e. No reactants remain.

Back 86

d. The rates of the forward and reverse reactions are equal.

Front 87

We can represent atoms by listing the number of protons, neutrons, and electrons -- for example, 2p+, 2n0, 2e-, for helium. Which of the following represents the 18O isotope of oxygen?

a. 6p+, 8n0, 6e-;

b. 8p+, 10n0, 8e-;

c. 9p+, 9n0, 9e-;

d. 7p+, 2n0, 9e-;

e. 10p+, 8n0, 9e-

Back 87

b. 8p+, 10n0, 8e-

Front 88

the atomic number for sulfur is 16. Sulfur combines with hydrogen by covalent bonding to form a compound, hydrogen sulfide. Based on the number of valence electrons in a sulfur atom, predict the molecular formula of the compound.

a. HS;

b. Hs2;

c. H2S;

d. H3S2;

e. H4S

Back 88

c. H2S

Front 89

What coefficient must be placed in the following blanks so that all atoms are accounted for in the products?

C6H12O6 --> ____C2H6O + ____ CO2

a. 1, 2

b. 3, 1

c. 1, 3

d. 1, 1

e. 2, 2

Back 89

e. 2, 2

Front 90

Hydrogen bonding -

Back 90

A type of weak chemical bond that is formed when the slightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond in another molecule or in another region of the same molecule.

Front 91

Adhesion -

Back 91

The clinging of one substance to another, such as water to plant cell walls by means of hydrogen bonds (water to polar surfaces).

Front 92

Cohesion -

Back 92

The linking together of like molecules, often by hydrogen bonding (water to water).

Front 93

Specific heat -

Back 93

The amount of heat that must be absorbed or lost for 1 gram of a substance to change its temperature by 1 degree celcius (calorie).

Front 94

Temperature -

Back 94

A measure of the intensity of heat in degrees, reflecting the average kinetic energy of the molecules.

Front 95

Heat -

Back 95

The total amount of kinetic energy due to the random motion of atoms or molecules in a body of matter; also called thermal energy. Heat is energy in its most random form.

Front 96

Hydrophilic -

Back 96

Having an affinity for water (water-loving).

Front 97

Hydrophobic -

Back 97

Having no affinity for water (water-fearing); tending to coalesce and form droplets in water.

Front 98

Colloid -

Back 98

A mixture made up of a liquid and particles (because of their large size) remain suspended rather than dissolved in that liquid.

Front 99

Solvent -

Back 99

The dissolving agent of a solution. Water is the most versatile solvent known.

Front 100

Solute -

Back 100

A substance that is dissolved in a solution.

Front 101

Solution -

Back 101

A liquid that is a homogeneous mixture of two or more substances.

Front 102

Aqueous solution -

Back 102

A solution in which water is the solvent.

Front 103

Molarity -

Back 103

A common measure of solute concentration, referring to the number of moles of solute per liter or solution.

Front 104

Molecular mass -

Back 104

The sum of the masses of all the atoms in a molecule; sometimes called molecular weight.

Front 105

Mole -

Back 105

The number of grams of a substance that equals its molecular weight in daltons and contains Avogradro's number of molecules (6.02*10^23 molecules)

Front 106

% solution -

Back 106

A solution containing a weight of a solute in grams divided by the volume of the solution in milliliters, multiplied by 100.

Front 107

Hydroxide ion -

Back 107

A water molecule that has lost a proton; OH-.